EVAPORATOR

PROBLEM TO BE SOLVED: To provide an evaporator, small in size, high in performance and excellent in temperature stability, by a method wherein a characteristic that the evaporator can supply a gas at a stabilized temperature while utilizing the high heat exchanging efficiency of a heat exchanger utilizing steam and the temperature stability of evaporated gas in a heat exchanger utilizing hot-water are combined. SOLUTION: A first constitution is provided with a main heat exchanging tank and a heat exchanging tank for regulating temperature, which are different in an evaporated gas temperature, to join and mix the evaporated gas from both heat exchanging tanks whereby temperature regulation is effected. A second constitution is provided with a first heat exchanger in a hot-water layer, a second heat exchanger in a steam layer and a third heat exchanger in the hot-water layer which are formed so as to conduct gas to flow in this sequence whereby the evaporator, utilizing the highness of the heat exchanging efficiency due to steam and the excellency of temperature stability due to hot-water, can be obtained.